A robot probe sent into the crippled reactor at Japan’s Fukushima Daiichi nuclear plant stopped working three hours into its 10-hour mission, but not before sending back the first pictures from inside.

The haunting grainy footage released by the Tokyo Electric Power Company (TEPCO) shows the robot moving through debris along a grated platform inside Fukushima’s No. 1 reactor. Steam is clearly shown rising from below where TEPCO believes the melted nuclear fuel rods are located.

One of the main objectives was to collect data on radiation levels inside the reactor. On the video’s onscreen display, the radiation levels ticked up as high as 9.7 sieverts per hour, which is high enough to kill a human within an hour.

Three hours into the operation, TEPCO said the robot became stuck and stopped operating. The robot developed by Hitachi was made to withstand high levels of radiation but it remains unclear why it stopped working. After attempts to retrieve the probe, TEPCO said it decided to cut off the cable connected to the device and abandon the robot inside.

A second robot mission scheduled for this week has been postponed as engineers investigate the cause of the malfunction.

TEPCO representative Teruaki Kobayashi said the silver lining of the operation was that officials found no major obstacles around an opening that leads to the underground part of the reactor. This will allow future robotic missions to possibly access the molten fuel rods for extraction.

The No. 1 reactor is one of three reactors at the Fukushima-Daiichi plant that experienced a meltdown during and in the aftermath of the March 2011 earthquake-triggered tsunami.